Mechanical ventilation with heat recovery (MVHR) replaces a home's air roughly every 2 hours; the Zehnder systems BIOBUILDS installs filter 99% of dust and allergens and recover ~95% of the heat in outgoing air. The German energy-advice portal co2online prices a central system for a single-family house at roughly €8,900-€15,600 installed; filter upkeep runs €50-€100 per year. Every BIOBUILDS turnkey home includes the factory-installed Zehnder system in the list price; for semi-finished homes, it is a per-model configurator upgrade.
Every airtight, well-insulated home needs a ventilation system; this guide covers that system and nothing else. What it is, what it costs to buy and maintain, and what it does all day. Related questions have their own guides: the effects of ventilation on the air you breathe are covered in the indoor air quality guide, the heating system that pairs with it is covered in the heat pump guide, and the resulting winter bills are covered in the heating cost guide. The case for building an airtight, certified envelope in the first place is made in the timber-frame and Passivhaus pillar guides; this article assumes that envelope and explains the component that makes it livable.
What is mechanical ventilation with heat recovery?
An MVHR system continuously does what opening a window does badly: it exchanges indoor air for outdoor air. Extract ducts pull stale, humid air from kitchens and bathrooms; supply ducts deliver fresh air to bedrooms and living rooms. Between the two streams sits a heat exchanger, where outgoing warm air and incoming cold air pass across a large transfer surface without ever mixing. The heat changes sides; the air does not.
That last step is the entire economic argument. A tilted window in January exchanges air at the cost of every degree of warmth in it. A heat exchanger keeps most of those degrees: according to co2online, modern residential units recover from 75 to over 90 percent of the heat, and the Passivhaus criteria require at least 75% effective recovery for certification. The Zehnder systems installed by BIOBUILDS, the European manufacturer publishing this guide and one of the best-priced in the certified segment, recover ~95%.
BIOBUILDS builds every model on a Passivhaus-certified building system designed around MVHR from the start: the Swiss-made Zehnder system (EVO on smaller models, ComfoAir Q450 with ComfoClime on Serenity and Sanctuary) arrives factory-installed in every turnkey home and is a per-model configurator upgrade for semi-finished homes.
How much does heat recovery ventilation cost in 2026?
For a buyer adding MVHR to a conventional project, the German market figures from co2online break down like this for a central system in a single-family house:
| Cost item | Market guideline | Notes |
|---|---|---|
| Planning | €400-600 | Duct routing and airflow calculation, done before the shell closes |
| Unit and materials | €6,000-9,000 | Central unit, ducting, valves, silencers, filters |
| Installation | €2,500-6,000 | Simplest in a new build, where ducts go in with the structure |
| Total, installed | ≈ €8,900-15,600 | Central system with heat recovery, single-family house |
Two notes on reading that table. First, it describes a central ducted system, the type worth having: decentralized single-room fans cost less but ventilate room by room instead of moving air through the home. Second, the installation range rewards timing. Ducts routed through an open structure cost a fraction of ducts retrofitted through finished walls, which is why the best moment to buy ventilation is before the house exists. For retrofits in existing buildings, Germany's BEG single-measure program refunds up to 20% of eligible costs as of 2026 (15% base, plus 5% with a renovation roadmap); the wider funding landscape is covered in the subsidies guide.
In a BIOBUILDS turnkey home, the table above collapses into the list price. The ducting is designed into the Passivhaus-certified building system, the Zehnder unit is mounted and commissioned in the factory, and every turnkey configuration arrives with the ventilation installed. For semi-finished homes, the same factory installation is a per-model upgrade, from €4,800 (Nest) to €18,800 (Sanctuary); the configurator shows the price per model and finish level.
MVHR appears as a five-figure extra only when ventilation is bolted onto a building that was designed without it. Designed in from the start, it is part of the turnkey price, and factory installation removes the largest cost variable: on-site duct labor.
Why an airtight home cannot skip mechanical ventilation
A Passivhaus-level envelope is verified by a blower-door test: the house is pressurized to 50 Pascals, and the certification limit allows 0.6 air changes per hour, while BIOBUILDS builds to an internal target of 0.4. That is roughly 30 times more airtight than a standard new build.
Airtightness at that level is what makes a heating demand of 15 kWh/m² per year possible, compared with roughly 350 kWh/m² per year for typical older European stock. But it also means the building no longer ventilates itself through leaks, and the leak-based alternative was never good: air through cracks arrives unfiltered, carries outdoor humidity into the structure, and takes indoor heat with it on the way out. Scheduled window ventilation has the same energy problem: every air change exhausts 100% of the heat in the outgoing air, several times a day, all winter.
MVHR solves both problems. The envelope ensures that air enters in exactly one place; the ventilation system routes it through a filter and heat exchanger. The home gets more fresh air than a windows-and-leaks house, at a small fraction of the heat loss. In summer, the system works the other way: a bypass routes night air around the exchanger to cool the home without importing daytime heat.
What the Zehnder system delivers and what it demands
- Heat retention: ~95% of the warmth in outgoing air is transferred to incoming air instead of vented
- Filtered supply: 99% of dust and allergens are stopped before air reaches the rooms, a measurable relief for pollen allergies
- Quiet: ventilating with windows closed preserves the BIOBUILDS envelope's 54 dB sound insulation around the clock
- Humidity control: continuous extraction from kitchens and bathrooms removes moisture before it condenses in the structure
- Negligible electricity use: the unit runs 24/7, silently, using about as much electricity as a light bulb
- Filter discipline: a neglected filter degrades airflow and filtration; the system's 10-minute filter changes must still be done
- Retrofit cost: in a finished conventional house, duct routing is invasive and sits at the top of the price ranges above
- Design dependency: undersized ducts or a unit squeezed in as an afterthought can cause audible airflow; quiet operation is planned, not automatic
- Not a heater: MVHR keeps heat in the house; it does not generate it. The envelope and heating system still have to do their jobs
MVHR maintenance and filter schedule
Maintenance is less demanding than most owners expect and consists almost entirely of filter changes. Here is the regimen, using co2online's market figures:
There is no seasonal shutdown, no refilling, no combustion service. The failure mode to avoid is a trivial one: filters left in place for years. Airflow drops, the fans work harder, and the filtration the system was bought for stops working. Put the filter dates in a calendar and the system is effectively maintenance-free between professional cleanings.
MVHR and the heat pump: two different jobs
The two systems are easy to conflate because they cooperate in a good home. The division of labor is strict: MVHR moves air and keeps existing heat inside; the heat pump generates the heat in the first place. In BIOBUILDS homes, the two are integrated, and because the ventilation returns ~95% of outgoing heat, the heat pump only ever tops up the small remainder, allowing it to stay small and inexpensive. Sizing, cost, and how a Passivhaus-level envelope shrinks the heating system are the subject of the heat pump guide.
